Photoinitiator anchored to silicate and use thereof to prepare polymer exfoliated silicate nanocomposite

Abstract

Photoinitiator modified silicate and ethylenically unsaturated monomer are reacted in solvent to cause living polymerization of monomer and exfoliation of silicate layers and cause attachment of silicate layers to polymer chains, thereby providing dispersed homopolymer or block copolymer silicate nanocomposites.

1. Photoinitiator for cation exchange attachment to a nanoclay comprising a photoinitiating moiety and a moiety for attaching to nanoclay by cation exchange. 
     
     
       2. The photoinitiator of  claim 1  where the photoinitiating moiety is a benzyl dithiocarbamate moiety and the attaching moiety is a benzyl trimethyl ammonium moiety. 
     
     
       3. The photoinitiator of  claim 2  which is 
       
         
           
           
               
               
           
         
       
     
     
       4. Nanoclay cation exchanged with the photoinitiator of  claim 1 . 
     
     
       5. The nanoclay of  claim 4  where the photoinitiating moiety of the photoinitiator is a benzyl dithiocarbamate moiety and the attaching moiety of the photoinitiator is a benzyl trimethylammonium moiety. 
     
     
       6. The nanoclay of  claim 5  where the cation exchange is with 
       
         
           
           
               
               
           
         
       
     
     
       7. Nanoclay partially cation exchanged with (a) photoinitiator of  claim 1  and partially cation exchanged with (b) organic cation that does not contain photoinitiating moiety where the mole ratio of a:b ranges from 10:1 to 1:10. 
     
     
       8. The nanoclay of  claim 7  where (a) is 
       
         
           
           
               
               
           
         
         and (b) is trimethylbenzyl ammonium chloride. 
       
     
     
       9. A method for preparing homopolymer or copolymer dispersed silicate nanocomposite from ethylenically unsaturated monomer and photoinitiator modified silicate or partially photoinitiator modified silicate comprising photopolymerizing ethylenically unsaturated monomer in solvent containing photoinitiator-modified silicate to cause living polymerization of the monomer, with polymer chains in a nanocomposite ionically attached to exfoliated silicate layers dispersed in a polymer matrix. 
     
     
       10. The method of  claim 9  where the solvent is a dipolar aprotic solvent. 
     
     
       11. The method of  claim 10  where photoinitiator modified silicate is present and is nanoclay cation exchanged with photoinitiator comprising a photoinitiating moiety and a moiety for attaching to nanoclay by cation exchange. 
     
     
       12. The method of  claim 10  where photoinitiator modified silicate is present and is nanoclay cation exchanged with 
       
         
           
           
               
               
           
         
       
     
     
       13. The method of  claim 10  where partially photoinitiator modified silicate is present and is nanoclay partially cation exchanged with (a) 
       
         
           
           
               
               
           
         
       
       and partially cation exchanged with (b) organic cation that does not contain photoinitiating moiety, where the mole ratio of a:b ranges from 10:1 to 1:10. 
     
     
       14. The method of  claim 10  where the ethylenically unsaturated monomer is selected from the group consisting of styrene, methyl methacrylate, tert-butyl methacrylate, n-butyl methacylate, 1,1,1,2,2-pentafluoropropyl methacrylate, (2-trimethylsilyloxy)-ethyl-methacrylate and tert-butylacrylate. 
     
     
       15. The method of  claim 14  where sequential monomer addition is employed either first producing silicate-polystyrene living block and then polymerizing methyl methacrylate from it or first producing silicate-poly(methyl methacrylate) living block and then polymerizing styrene from it. 
     
     
       16. Admixture for polymerization comprising ethylenically unsaturated monomer and photoinitiator modified silicate or partially photoinitiator modified silicate, in a weight ratio ranging from 400:1 to 1:2. 
     
     
       17. Dispersed poly(ethylenically unsaturated monomer) photoinitiator modified silicate or partially photoinitiator modified silicate nanocomposite where polymer chains are attached to photoinitiator modified silicate, where the weight ratio of polymer to photoinitiator modified silicate or partially photoinitiator modified silicate ranges from 400:1 to 1:2. 
     
     
       18. Dispersed poly(ethylenically unsaturated monomer)-block-poly(different ethylenically unsaturated monomer) photoinitiator modified silicate or partially photoinitiator modified silicate nanocomposite where one end of the first block polymer chain is attached to photoinitiator modified silicate and where the weight ratio of block copolymer to photoinitiator modified silicate or partially photoinitiator modified silicate ranges from 400:1 to 1:2, and where the volume ratio of poly(ethylenically unsaturated monomer) to poly(different ethylenically unsaturated monomer) ranges from 1:5 to 5:1.